package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;


import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock{
    private String name;
    private StringRedisTemplate stringRedisTemplate;

    public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
        this.name = name;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    private static final String KEY_PREFIX = "lock:";
    //给线程随机生成一个id
    private static final String ID_PREFIX = UUID.randomUUID().toString(true)+"-";
    //初始化lua脚本
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    //加载lua脚本
    static{
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }
    @Override
    public boolean tryLock(long timeoutSec) {
        //获取线程表标识
        String threadId= ID_PREFIX+Thread.currentThread().getId();
        //1.获取锁
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
        //用TRUE.equals(success)判断，防止自动拆箱是出现错误 如果是null返回的也是false,防止出现空指针异常
        return Boolean.TRUE.equals(success);
    }
    @Override
    public void unlock() {
        //基于lua脚本进行执行（由原来的两行代码改为一行代码，防止出现线程安全问题） 判断是否是同一个线程是在lua脚本中，符合原子性
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                //获取锁中的线程标识，并放入到一个集合当中
                Collections.singletonList(KEY_PREFIX + name),
                ID_PREFIX+Thread.currentThread().getId());
    }
   /* @Override
    public void unlock() {
        //获取线程标识
        String threadId= ID_PREFIX+Thread.currentThread().getId();
        //获取锁中的线程标识
        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
        //判断是否一致
        if(threadId.equals(id)){
            //一致释放锁就行
            stringRedisTemplate.delete(KEY_PREFIX + name);
        }

    }*/
}
